Do some research towards the exact vitamin components in the OTC product and what are considered "state-of-the-art" vitamin components. You will probably find many (types of) discrepancies:
- Inferior (synthetic) vitamin components in some of the OTC products that lag behind current scientific insights.
- Current scientific insights do lag behind "reality". We only know what we know.
- The fact that the current scientific insights regarding vitamins are by no means generally accepted in the scientific community. Due to the lack of research that has sufficient credibility towards beneficial effects in humans.
- And due to the fact that "politics" is still greatly involved in the interpretation of research results, which is partly enabled by the fact that evidence has not been sufficiently proved beyond any doubt, if that would be possible at all in general.
- Studies that are "poorly" designed if you take into account the beneficial effects in "normal" humans. The goal of the research is not always the goal of the general interpretation that is given to research results. Jumping to conclusions to soon.
- The individual needs for vitamins is, yes, individual.
Just skim the threads here (and elsewhere) to try to form your own opinion on what might be good for you. Dispite the somewhat negative appraoch above, I think vitamine use is benificial if you do it in a smart way. There's no short answer if you ask me and I cannot be smart for you.